great game!
I found a bug on level 6: if you jump over the keyhole you can cross the ceiling all the way to your doom on the bottom pit.
There's alot more than that. While I was playing Level 6, I completely broke it. The enemies wouldn't move, and I could push them - yes, even the spiked turtles. The spikes, falling-out-of-the-world by this mentioned glitch, and, while I admittingly didn't test it, presumably the lava could kill however.
Some screenshots of the madness;
All enemies frozen, can stand on turtle.
Can't pick up the key (the level's unbeatable as a result)
Moving the spiked enemies, standing next to one without dying.
Reset button doesn't work - the pink turtle's next to the button, barely seen in the screenshot.
This is how the glitch dangpzanco mentioned is done.
Btw, I still loved the game regardless; it was very fun and unique. I have a tendency to break games, even when I try to play them as intended. Unfortunately, I have no idea how I accomplished this glitch (beyond what dangpzanco mentioned).